Anybody good at reading plugs?

I don’t have any info to back this up, and it’s just a guess. I’m betting that if higher resistance plugs that cross referenced to stock plugs really increased the temperature enough to melt a wiring harness that there would be quite a few people who’d experienced it, and that different resistance plugs wouldn’t show up when you looked up suitable plugs for the engine. I’d guess that resistance would be one the criteria by which plugs got sorted. I’d also bet that NGK, Bosch, etc. would get in trouble for marketing them as replacements. Rock Auto, AutoZone, and Oriely’s all list the plug I used when looking up by year, make and model. If the coil won’t run the extra resistance, if the input to the coil needs to be different, or something about the plug causes performance issues, then sure I need to go with copper. On the other hand, if the engine is going to run exactly the same way, and guys who supercharged their truck are running iridiums without melting their wiring, then I really don’t see that as a likely problem.

Has anyone melted the wires that go to their coil packs on any vehicle by using the a different plug?

 

I held out for the manual v6 and it was worth the wait BUT if you were ever to regear the truck, you'd get much better "performance" and gas mileage, especially if you want to add any more weight to the vehicle (i.e. steel bumpers, camper top, winch, ect...)

 

Like I said before, the definite answer will not come without access to the engineering documents. I wish I had a more concrete answer for you but it was merely speculation. It's Russion roulette, if out of 100 people that have non-recommended plugs for their vehicle and only 1 vehicle burns down due to those plugs. It's just a risk, thats all. Dont take this as a personal attack towards your views, this isn't that. If companies are selling iridium plugs marketed towards the 4.0 then they might know something that we dont or are financially liable for any failures from their equipment. Honestly, I dont know for certain as I stated in my previous reply above. Companies sell tire slime for quick repairs when it prevents the tire from being permantly repaired and gums up TPMS sensors but it's still sold in stores. Tire repair shops hate and love it because they get to sell new tires instead of a simple inexpensive rubber patch job. This is merely an example of just because something is sold doesn't mean it should be used. Do not get me wrong, I'm not trying to tell you that you're wrong per say, I'm just merely trying to make sure that the correct information gets out there in the event that someone else has a similar issue/idea.

-J

 

I changed my OEM plugs at 30k per the recommended schedule. Changed them again at 60k. Both times I went with NGK G-Power. I don't believe they're iridium though...they're platinum.

My 4.0 runs flawlessly.

 

I don’t have any views on iridium plugs other than that they last longer. If they’d cause an engine problem I’d yank them. As far as melting wiring, there are millions of cars in the USA if .1% of the cars with a different style plug that cross referenced to be a suitable replacement for the OEM plug ended up with melted wiring, it would be a well known issue. With zero science to back me up. I’m not particularly worried about my wires melting from using iridium plugs. There does seem to be some evidence of an injector issue. Once I think that’s cleared up, if the truck still fails to produce the fuel economy that a stock 4.0 should or begins to exhibit any other sort of problem, then I might look at switching to copper before the iridiums wear out.

Another guess would be that improved intake port and combustion chamber design, coupled with modern port fuel injection, distributorless ignition monitored by the ECU, and individual coils with no wires have dramatically reduced or eliminated the advantages of a copper plug. I really don’t know. Just a guess.

 

If you replaced your platinums with platinums at 30k, then you probably didn't need to do that. Platinum plugs are rated upwards of 100k to 120k miles before needing replacement, again as long as they are gapped appropriately. IIRC, platinum plugs come pre gapped since platinum is a very hard yet brittle metal. This means that you might break the grounding strap if you attempt to adjust the gap. Typically, if you get a platinum plug that has an incorrect gap to exchange it for a properly gapped plug. Again, I have zero experience with Platinum Plugs.

-J

 

Wow, nice entitled attitude....

 

How is that entitled? I open a thread asking if it looks like I may have a cylinder or two that’s running rich, 9/10 people answer things completely unrelated to the question, the majority of the forum is about modding these trucks and doing things very differently from the manual, and everyone who says “don’t use iridium” when asked “why not” says “I don’t know...the manual references a plug that happens to be copper”, which frankly is a lot different than if the manual said “use only copper plugs” or “do not use iridium plugs”.

The manual on my 2010 2.7l says to use 0w-20 or 5w-20 motor oil. When I bought it in 2010 i e-mailed Toyota and asked if anything bad would happen if a ran a heavier oil. Their answer was “your engine will be better protected, will probably last longer, and may suffer a slight reduction in fuel economy”

 

You should call up a veteran Toyota engineer team and directly ask them your questions. Have a sit down panel interview. Until then, asking a forum will get you all of the answers you're getting. Best of luck.

 

So I ask question A, people answer question B(which I did not ask) with very limited info to back up their answer. Someone eventually answers question B with extensive information and background. I compliment them for standing out as being more knowledgeable, and you decide that me applauding the person that stood out as a sign that I have an entitled attitude. Hmmm.

 

Yep. Well aware of that. Definitely don't want to try and gap platinums. I also understand that replacing them at 30k is usually early. It was more just wanting to see what they would look like after that mileage. They looked great BTW...much better than the copper OEM plugs I pulled at 30k.

But I went ahead and replaced them anyway, as I already had the new ones.

This time....I will go much longer on this 2nd set.

 

Regarding the bolded section above; my manual’s (2015) pretty clear in stating iridiums are for the 2.7 only:
NOTICE
■ Iridium-tipped spark plugs (2.7 L 4-cylinder [2TR-FE] engine only)
Use only iridium-tipped spark plugs. Do not adjust gap when tuning engine.

As for the 9 out of 10 answering your questions, IMHO you should be thankful for any response. The fact someone opened your thread and took the time to type in a response is amazing. Off topic responses can give you something compelling to think about. For example, my tagging a transmission expert to weigh in about changing your transmission fluid...Is that grouped in with the 9 out of 10?

It’s interesting too you focused in on “entitled” but didn’t deny the “attitude”...

 

If you read the portion of the manual that you quoted, it means that the statement “use only iridium tipped spark plugs” applies only to the 2.7L 4-cyl. It does not mean, “use iridium tipped spark plugs only in the 2.7L 4-cyl”. Those two things are different. The manual does not say not to use iridium tipped plugs in the V6.

 

I think I see 3 Densos and 3 NGKs. If that's the case, then those were the factory plugs. They look pretty good to me for old worn out copper plugs. I think you're good.

I personally see no reason you can't run whatever plug you want, BTW.

 

It’s probably all the extra rotational mass from the 80psi of air in each tire. Sorry I had to.

 

As funny as it may be, this just further illustrates the lack of attention that has been payed by many of the people responding to this thread. There is not(yet) 80psi in the tires on the truck those plugs came from.

 

Everyone, go stand in the corner


BTW, if you go ahead with your plan to push them to 80 PSI, the manual (at least the ‘15) states the TPMS system is disabled at 73 PSI. I don’t know why though 1 out of 10 future responses might be on point and be helpful to you.

 

Nah I didn’t say anything about attitudes but good try. Just saying that when you post a question on forums, you get all types of answers. Good and bad. I honestly hope you get good responses on here. But don’t act shocked you get ones you don’t like. You opened the door about psi and people take their stance and personal opinion and general safety ideals here. Don’t get mad about that. Ultimately, if you don’t like a response, ignore it and move on.

On that note, your plugs don’t look horrible overall and replace with what you feel is the best option based off of what you have researched and general knowledge.

 

Looking at short/long term fuel trims would tell you everything you need to know about the mixture

Unburned fuel (usually from lack of spark) is what takes out catalytic converters. They will glow like a jack-o-lantern. note that there is a difference between excessively rich mixture going through the engine and (liquid) unburned fuel making its way into the exhaust pipe

It was probably those original/shitty plugs that took out the converter. The bad plugs resulted in a heavy misfire, which resulted in liquid fuel going straight into the cats.

Previous owner was neglecting the truck

 

That’s hasn’t happened on my 2010, but it would be a heck of a good reason to run less pressure. If it happens on the 2008 at some point, then this bit of info will help me a avoid a bit of a head scratcher. Thanks.